1) Field of the Invention
The present invention relates to technologies which control performance levels of an electronic device operated by a battery. The invention relates particularly to a performance controller, a performance controlling method, and the computer program product which can operate a battery efficiently according to performance and operating time which are demanded by users for an electronic device driven by the battery.
2) Description of the Related Art
In recent years, according to miniaturization and power saving of electronic devices, utilization of mobile electronic devices such as laptop personal computers (hereinafter, “laptop PCs”) increases rapidly. In such mobile electronic devices, it is important to use batteries efficiently, and to lengthen their operating times.
In mobile applications, since battery shutoff during use greatly deteriorates operating efficiency, it is very important for users how long batteries can run, namely, how long the mobile electronic devices can be used. Further, it is also very important for users that the mobile electronic devices can be used while their performance is being maintained as high as possible for a time when batteries keep running.
Normal mobile electronic devices, therefore, have functions which display a percentage of residual charge level of the battery, and when the residual charge level reaches a value equal to or smaller than a predetermined value, give an alarm. Further, normal mobile electronic devices have functions which classify performance of main components such as central processing unit (hereinafter, “CPU”) and a liquid crystal display (hereinafter, “LCD”), and electricity consumption in conjunction with the performance by a plurality of levels, and adjust the performance levels so as to adjust the power consumption of mobile electronic devices.
Only with the display of the residual charge level and the adjustment of the performance level of the main components, however, users can only estimate residual battery available time, but cannot know accurate battery available time.
For example, therefore, a following technique is disclosed. In this technique, when users set desired battery operating times, electricity consumption of electronic devices is controlled so that the best performance is given for a time when the operating times are guaranteed (for example, see Japanese Patent Application Laid-open No. H5-307431).
Only when the electricity consumption of the mobile electronic devices is controlled so that the best performance is given for a time when the operating time of batteries are guaranteed, however, the mobile electronic devices are always used with the same performance. This deteriorates the usability of batteries.
That is to say, performance which is required when mobile electronic devices are used greatly differs according to applications to be used. Accordingly, under a condition that the mobile electronic devices are always used with the same performance, the performance becomes insufficient when applications with high load such as video play are executed. Moreover, when applications with low load such as word processing are executed, electric power consumes unnecessarily. In order to improve the usability of batteries to be used in mobile electronic devices, therefore, it is important to control the performance level after the load of applications to be executed is taken into consideration.